Hopefully it happens, and all of the people threatening to quit actually do. It'd be nice to stop seeing you in-game and on the forums.
On a lighter note, I can get behind the idea. Been playing Rift recently and I like the concept a lot. I think other games like League of Legends do it well too, but since we're talking a different genre, it isn't as applicable. In the end, Blizzard will do whatever is best for the longevity of their game, and I could see this being a good choice.
You get that most free to play that add this and make leveling a pain right? like grind or quests/mobs give low exp? hence force you to buy it so you get a chance to catch up, that's why most of us choose a monthly fee game and not get pay-to-win.... Useless pets are ok but pay to win isnt.